JPH07121036A - Transfer device - Google Patents

Abstract

PURPOSE:To provide a transfer device capable of preventing the occurrence of an image defect when used in an image forming device such as copying machine. CONSTITUTION:In the transfer device A', when a guiding insulated-sheet 4, which guides transfer paper 2 so that transfer paper 2 adheres to a photoreceptor 1, is provided right in front of a transfer part 3 used for transferring a latent image formed on the photoreceptor 1 onto the transfer paper 2, the thickness of the front end part of the guiding insulated-sheet 4 is made smaller than its root part. In the above structure, an increace in contact area between the paper and the sheet which is caused when the guiding insulated- sheet is shaved off by the passing of the paper can be prevented. Therefore, the occurrence of static electricity and defective discharging of the photoreceptor 1 are suppressed, and, as a result, the occurrence of an image defect can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device, and more particularly to a transfer device used in an image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art Generally, a transfer device A of this type is used in an image forming device such as a copying machine, and as shown in FIG. 3A, a latent image formed on a photosensitive member 1 is visualized by toner. After the image is formed, the toner image is transferred to the transfer paper 2 which is the final image support. In order to perform this transfer, a transfer portion 3 having a transfer wire for corona discharge is provided inside a shield case formed in a so-called corotron system having a substantially U-shaped cross section. As shown in the figure, the transfer portion 3 is often formed integrally with a separating portion having a similar structure and provided with a separating wire. In order to reliably transfer the toner image on the photoconductor 1 to the transfer paper 2 by the transfer unit 3, it is necessary to bring the transfer paper 2 into close contact with the photoconductor 1 at the time of transfer. Therefore, a guide insulating sheet 4 for guiding the transfer sheet 2 to the photoconductor 1 is provided immediately before the transfer section 3. The guide insulating sheet 4 usually has a thickness of about 0.2 mm and is supported by the guide plate 5. The rigidity of the insulating guide sheet 4 ensures the close contact between the transfer sheet 2 and the photoconductor 1 that come into contact with the leading end of the insulating sheet 4.

[0003]

In the conventional transfer apparatus A as described above, the leading end of the guide insulating sheet 4 is scraped by the transfer paper 2 as the sheets are passed, and the contact between the paper and the sheet is caused. The area gradually increases (Fig. 3 (b),
(See (c)). Therefore, static electricity due to friction is easily generated between the transfer paper 2 and the guide insulating sheet 4. As a result, abnormal discharge to the drum may occur, and abnormal images (pinholes, etc.) may occur. The present invention has been made in view of the above circumstances, and an object thereof is to provide a transfer device that does not cause an abnormal image when used in an image forming apparatus such as a copying machine.

[0004]

In order to achieve the above-mentioned object, the main means adopted by the present invention is, in summary, just before the transfer portion for transferring the latent image formed on the photoconductor onto a sheet. Further, in a transfer device provided with a guide insulating sheet for guiding the sheet so that the sheet is brought into close contact with the photoconductor, the thickness of the guide insulating sheet is set so that the tip portion is thinner than the root portion. The transfer device is characterized in that

[0005]

In the transfer device according to the present invention, for guiding the paper so that the paper is brought into close contact with the photoconductor immediately before the transfer portion for transferring the latent image formed on the photoconductor to the paper. An insulating sheet is provided, and the thickness of the guide insulating sheet is formed such that the tip portion is thinner than the root portion. For this reason, when the paper is passed, the tip portion is bent and is less likely to be scraped, so that the contact area between the paper and the guide insulating sheet is not increased, and as a result, the generation of static electricity is suppressed. Further, since the rigidity of the insulating guide sheet is maintained at the root portion, the rigidity of the guide insulating sheet can ensure the adhesion between the paper and the photoconductor. As a result, it is possible to prevent abnormal discharge to the photoconductor and abnormal images due to the discharge.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. The following embodiments are examples of embodying the present invention and are not intended to limit the technical scope of the present invention. Here, FIG. 1 is a schematic view showing a schematic structure of a transfer device A'in one embodiment of the present invention, and FIG. 2 is an example view showing a side cross section of another guide insulating sheet applicable to the transfer device A '. is there. Figure 1
As shown in (a), the transfer device A ′ according to the present embodiment transfers the transfer paper 2 to the photoconductor 1 immediately before the transfer unit 3 that transfers the latent image formed on the photoconductor 1 to the transfer paper 2. This is similar to the conventional example in that a guide insulating sheet 4 for guiding the transfer paper 2 so as to be in close contact is provided. However, the present embodiment is different from the conventional example in that the thickness of the insulating guide sheet 4 is smaller at the tip portion than at the root portion. Here, the guide insulating sheet 4 is composed of two relatively thin sheets,
The leading end of the insulating sheet on the most upstream side in the conveying direction of the transfer sheet 2 is projected from the leading ends of other insulating sheets. The thickness of both sheets may be about 0.1 mm. The operation of this device A'will be described below. That is, the transfer sheet 2 supplied from a sheet feeding device (not shown) is sequentially conveyed to the photoconductor 1 by the guiding insulating sheet 4. At this time, the contact portion between the transfer paper 2 and the guide insulating sheet 4 is only the most upstream insulating sheet in the transport direction. Since the insulating sheet is relatively thin as described above, the tip portion is easily bent by contact with the transfer sheet 2 (see FIG. 1).
(See (b)). Therefore, the abrasion by the transfer sheet 2 is less than that in the conventional example, and the contact area between the transfer sheet 2 and the guide insulating sheet 4 is kept substantially constant. This means that generation of static electricity due to friction generated between the transfer sheet 2 and the guide insulating sheet 4 is suppressed. as a result,
It is possible to prevent abnormal discharge to the photoconductor 1 and an abnormal image (pinhole or the like) due to the discharge. Further, by making the root portion of the guiding insulating sheet 4 thick, it is possible to provide the same rigidity as that of the conventional example, so that it is possible to secure the adhesion between the photoconductor 1 and the transfer paper 2.

Further, since the guide insulating sheet 4 is less scraped, the life of the guide insulating sheet 4 can be extended. This also has the advantage of maintenance. By the way, in the above embodiment, the guide insulating sheet 4 is composed of an insulating sheet having a relatively small thickness, and the insulating sheet is projected more than the insulating sheet. However, as shown in FIG. The sheet may be projected from the insulating sheet. Further, in the above-mentioned embodiment, the insulating sheet is used as the relatively thin sheet, but the number may be further increased. The sheet is for example 5/100
Some of them are as thin as about mm, and the desired performance can be obtained by combining them with an appropriate thickness. Further, the guide insulating sheet 4 does not necessarily have to be composed of a plurality of sheets. For example, as shown in FIGS. The same performance as can be secured.
In addition to this, it is possible to gradually reduce the thickness from the root portion to the tip portion, or to provide a curved surface. As described above, when the present invention is applied to an image forming apparatus such as a copying machine, it is possible to prevent the contact area between the sheets from increasing due to the abrasion of the guiding insulating sheet due to the passage of the sheet. Therefore, it is possible to obtain the transfer device in which the generation of static electricity and the abnormal discharge to the photoconductor are suppressed, and as a result, the abnormal image is not likely to occur.

[0008]

Since the transfer device according to the present invention is configured as described above, when it is applied to an image forming apparatus such as a copying machine, the insulating sheet for guiding is scraped by passing a sheet to cause a gap between sheets. The contact area can be prevented from increasing. Therefore, it is possible to obtain the transfer device in which the generation of static electricity and the abnormal discharge to the photoconductor are suppressed, and as a result, the abnormal image is not likely to occur.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of a transfer device A ′ according to an embodiment of the present invention.

FIG. 2 is an example view showing a side cross section of another guide insulating sheet applicable to the transfer device A ′.

FIG. 3 is a schematic diagram showing a schematic configuration of an example of a conventional transfer device A.

[Explanation of symbols]

 A '... Transfer device 1 ... Photoconductor 2 ... Transfer paper (corresponding to paper) 3 ... Transfer part 4 ... Insulating sheet for guide

Claims (1)

[Claims] 1. A transfer device having a guide insulating sheet for guiding the paper so that the paper is brought into close contact with the photoconductor, immediately before a transfer unit for transferring the latent image formed on the photoconductor to the paper. 2. The transfer device, wherein the thickness of the guide insulating sheet is set such that the tip portion is thinner than the root portion.